"They are metal stairs, so it can be painful. It's coming to him from all angles." a source told IBTimes UK of the latest attack. "He's not popular at all and there apparently others waiting for him if he gets transferred to a different prison."

This second incident means it is time for the 46-year-old to ask the authorities to move him on to the vulnerable prisoners (VP) wing, said Steve Dagworthy of Prison Consultancy.

"I would consider starting to ask for a move because the prison authorities' job is to keep inmates safe, which isn't happening," he said.

Winning a transfer to a different part of Belmarsh would have the benefit of also getting Coulson away from his current cell mate, former colleague Neville Thurlbeck, a senior reporter under him at the NoW.

Thurlbeck was sentenced for six months at the same Old Bailey trial as Coulson.

According to Private Eye, the pair are cooped up together in a hot, tiny cell for hours on end, which is bound to be awkward, considering how they condemned one other during the phone-hacking trial.

At the Old Bailey, Coulson claimed Thurlbeck carried out the only incident he knew about of phone hacking at the NoW and that he halted it.

In contrast, Thurlbeck testified that Coulson knew hacking was rife and never lifted a finger to stop the illegal practice. Thurlbeck's lawyer told the court: "No disapproval of the practice was given by Mr Coulson."

Prime Minister David Cameron's former confidante remains in Belmarsh and not a lower category jail, where he would be safer from attack. That is because there remain outstanding charges against him, which means he is ineligible for a transfer.

Meawnhile, as he recovers from his tumble down the stairs, two more senior former colleagues of Coulson were arrested under Operation Pinetree, a Met Police investigation into allegations that NotW features staff obtained information via phone hacking.